"This case was particularly unsettling because the suspect seemingly targeted random victims with no apparent pattern," he said yesterday in a press statement. "Police intensified patrols on the ground because we knew we had to catch him quickly before more members of the public got hurt."

One of the alleged victims, Mr See Han Sern, posted details of the attack on his Facebook account, saying he was stabbed twice in the back at about 9am while on the way to breakfast with his parents.

The man was wearing a dark blue-grey checked shirt and long black pants, and had allegedly attacked him in front of Chung Cheng High School along Yishun Street 61, wrote Mr See.

He added that the attack near a zebra crossing was "unprovoked".

He told The Sunday Times: "I have never met this man before and I was confused and angry. However, I backed down when I saw a sharp object in his hands.

"When the driver of a van asked the assailant to stop, he charged at him, causing the driver to speed away. The assailant then walked towards Block 635."

This article was published on April 13 in The Straits Times.Get a copy of The Straits Times or go to straitstimes.com for more stories.